35
Colloques Phytosociologiques
XXIX
Stelvio ’70
Camerino 2013
ECO-BIOGEOGRAPHICAL AND URBAN PARAMETERS
OF DIVERSITY, AREA, ISOLATION AND INTERFERENCE
FOR THE PLANNING INSTRUMENTS
Corrado BATTISTI *
Bernardino ROMANO **
*Ufficio Conservazione Natura
Provincia di Roma
Via Tiburtina, 691
00159 Roma
[email protected]
** Università dell’Aquila,
P. le Pontieri, 1, Monteluco di Roio
67100 L’Aquila
[email protected]
ABSTRACT
The impacts analysis of the fragmentation processes on biological diversity is
a priority in the context of the conservation initiatives. The environmental planning,
since some years, has a main goal that is the mitigation of fragmentation impacts by
means the integrate researches between territorial and environmental sciences and an
action on control instruments of territorial transformations. The clear goal of these
researches, now in progress, is that to establish the links between the rules of urban
planning - relative to the civic quality of the cities and territories - and the effects on
the ecosystem structure due to urban evolution. Is particularly important to know
and draw the environmental condition before and after the anthropic transformations
through coherent indices.
RÉSUMÉ
Paramètres éco-biogéographiques et urbanistes de diversité, surface, isolement et interference pour l’instrument de planification. L’analyse des effets du
processus de fragmentation sur la diversité biologique, aux différents niveaux hiérarchiques, constitue une priorité de conservation. La planification de l’environnement, à
travers le secteur disciplinaire de la chaîne écologique, a comme objectif la mitigation
de ces effets au moyen de stratégies territoriales. Les sciences naturelles et celles de la
planification sont à la recherche des paramètres qui supportent l’analyse du processus
et la définition des stratégies appropriées. Parmi ces paramètres quelques-uns, déjà
connus depuis longtemps et utilisés classiquement dans les secteurs disciplinaires
respectifs, peuvent être utilisés selon une clef de lecture rapportée aux thèmes de la
fragmentation e de la chaîne écologique.
36
RIASSUNTO
Parametri eco-biogeografici ed urbanistici di diversità, area, isolamento e interferenza per gli strumenti di pianificazione. L’analisi degli effetti del processo
di frammentazione sulla diversità biologica, ai diversi livelli gerarchici, costituisce
una priorità di conservazione. La pianificazione ambientale attraverso il settore
disciplinare delle reti ecologiche, ha come obiettivo la mitigazione di tali effetti
attraverso strategie territoriali. Le scienze naturali e quelle della pianificazione sono
alla ricerca di parametri che supportino l’analisi del processo e la definizione di
appropriate strategie. Tra questi alcuni, noti da tempo e classicamente utilizzati nei
rispettivi settori disciplinari, possono essere utilizzati secondo una chiave di lettura
riferita ai temi della frammentazione e delle reti ecologiche.
INTRODUCTION
The impacts analysis of the fragmentation processes on biological diversity is
a priority in the context of the conservation initiatives (FAHRIG, 2003; BATTISTI,
2003, 2004). The environmental planning, since some years, has a main goal that is
the mitigation of fragmentation impacts by means the integrate researches between
territorial and environmental sciences and an action on control instruments of territorial transformations (ROMANO, 2000).
To obtain these results it’s necessary to implement methods and criteria for identifying the relation among the parameters which describe status and evolutions conditions of the biological components and the settlement transformation phenomena.
The clear goal of these researches, now in progress, is that to establish the
links between the rules of urban planning - relative to the civic quality of the cities
and territories - and the effects on the ecosystem structure due to urban evolution.
Is particularly important to know and draw the environmental condition before and
after the anthropic transformations.
Since some years is in progress the proofs to realize a conceptual and experimental union between two thematic sets of indices (BATTISTI et al., 1999; BIONDI
et al., 2003), but we cannot say now to have reach the efficient results, because we
have again methodological and instrumental difficulties.
The objective of this contribute is to reorganize the framework relative to the
parametric links among eco-biogeographical and urban pattern indices with awareness to be in front of instruments which have numerous problems: the urban indices
are used by many decades and control, with different ways and efficiency, shape and
structures of the Italian urban landscapes.
The ecological and bio-geographical indices, even if are not recent (they have
been formulated, more less, at the same time of the others) have been implemented
and developed mainly in the scientific context and just in few cases in the concrete
context. Many of these last indices could be used to evaluation the environmental
fragmentation conditions (area reduction, increasing of isolation degree, environmental quality reduction - BENNETT, 1999).
Even if, for the cited reasons, the contents of this paper have to be inserted in
the proof and experimentation category, we can scheduled the parameters that could
be possible use for implementing the eco-bio-geographical-urban dialogic protocol.
The following parameters are applied to spatial units as environmental systems
37
Fig. 1. The flowchart shows the planning methodological lines by traditional key (narrow arrows) and an alternative hypothesis of these logical lines for involving, in the planning process,
the needs of biodiversity conservation and ecological assessment (bold arrows). [en couleur
à la page 776]
and subsystems, physiographic units, landscape units, ecosystems, remnant fragments
or, in some cases, to administrative surfaces (regions, provinces or municipalities) also.
ECO-BIOGEOGRAPHICAL PARAMETERS
Area/species relationship (MACARTHUR and WILSON, 1967): In 1970s theory of
insular biogeography was applied to continental lands (e.g., in fragmented landscapes
or nature reserve systems; DIAMOND, 1975; BURKEY, 1989). Z coefficient in logtransformed equations (log S = log c + z log A) is strictly linked to insular degree of
the system analyzed (geographical or ecological archipelagos). In ecological island,
embedded in anthropogenic transformed landscape matrix, this relationship should
reflect the classic one only considering the pre-fragmentation set of species. Species
could be qualitatively separated following their specific suitability for anthropically
transformed habitat (matrix: e.g., edge species) or natural remnant one (fragments;
e.g.: interior species: WILCOVE et al., 1986; VILLARD, 1998), obtaining species
richness values for specific subset of species (edge and interior species richness) at
fragment scale and assessing the relative area and isolation effect.
Area/isolation patterns (LAMBECK, 1997): here, spatial parameters of each ecosystem fragment are reported on a Cartesian space emphasizing the first predictor
inducing variations on dependent variables (number of species, abundance of individual species). Area/isolation patterns are useful for highlighting the different role
38
Fig. 2. Area/species diagram.
of these spatial parameters at population and community level and threshold values
in terms of sensitivity to area and isolation for specific taxa. Species could be also
subdivided in subsets (analysis at community level for ecological island; e.g. edge
or interior species: see above).
Abundance/richness diagrams (CONTOLI, 1988, 1991; BATTISTI et al., 1997):
these diagrams are utilized in biogeography at national/regional spatial scales. Lines
are relative, e.g., to archipelagos of remnant fragments in mainland and could be
useful to highlight insularity/peninsularity of a single system or their isolation/continentality. Increasing the slope of lines, the continentality degree increase. Abundance
should be ln-transformed.
Evenness (E)/normalized species richness (S) diagram (BATTISTI and CONTOLI,
1997): In ecological island (i.e., fragments), communities have a lower species richness and a higher evenness compared to communities in not fragmented/continental
systems. Consequently, location in a Evenness/species richness Cartesian space of
the communities could explain the isolation degree of the systems. Abundance/species richness and evenness/species richness diagrams should be useful to indicate
the isolation degree of the studied system at biogeographic (national/regional) scale.
Comparisons among communities in fragmented archipelagos and in not fragmented
territorial sectors are requested in order to acquire different patterns (maximum
values of Shannon diversity index is in the high-right side of the diagram; see fig. 4).
Diversity/dominance diagrams: Diversity/dominance diagrams are useful to esplicitate diversity index (e.g., Shannon) in a graphic form. A type of these diagram, rank
the frequency distribution of the species (higher to lower) (ODUM, 1988; BEGON et
al., 1986). Trends obtained show a general information on the state of the community:
e.g., slope of these lines may indicate natural or anthropogenic disturbances on studied
set of species. Habitat fragmentation could be considered as a complex disturbance
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Fig. 3. Pattern area-isolation diagram. Size of the plots is related to dependent variables as
species richness and abundance of individual target species or groups.
Fig. 4. Abundance (ln n. ind.; ln number of individuals)/species richness (S).
process composed by different components (BENNETT, 1999) and can intervene on
the slope of the lines (e.g., for area and isolation parameters). Area reduction of the
habitat fragments could induce change in community structure in terms of frequency
distribution). This “area effect”, quantified by evenness index, can be expressed in a
graphic form by frequency/rank diagrams (a form of diversity/diagrams).
40
Fig. 5. Evenness/species richness diagram.
Fig. 6. Relative frequency/rank for two communities submitted to different spatial/disturbance
conditions.
URBAN SETTLEMENT PARAMETERS
Urban density (UD): this index can be implemented in different ways in relation
with the GIS data which are available on study area. In its easier form the index
represent the surface percent covered by builds in relation with the entire surface
41
of the considered spatial unit (mq/ha). The significance of the UD index is directly
linked to the urban sprawl and it is possible to have further information if exist data
on builds destination (residential, productive, utilities, and so on), on the builds
volume and inhabitants number (in this case could be highlighted the extensive and
intensive urban conditions).
The use of the UD index is particularly interesting on landscape units because there
are important relations between landscape kinds and settlement kinds in qualitative
and quantitative terms.
Urban dispersion (URD): this parameter regards the distribution of urban nucleus
(obtained as centroids of the different urban areas polygons) within the considered
spatial units. It is possible to have the simple formulation of URD (e.g number of
nucleus/units area), or other formulation that could consider the distances among the
nucleus. The URD data have to be interpreted together the UD because to give the
Fig. 7. Example of relation between population increasing and urban surface evolution (18912001) in Conegliano Veneto, a municipality sited in Veneto region (Italy).
Fig. 8. Relation between urban surface evolution and people density decreasing (1891-2001)
in Conegliano Veneto, a municipality sited in Veneto region (Italy).
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Fig. 9. Tri-dimensional models of increasing territorial urban density from UD=15 mq/ha (high
to left) to UD=1000 mq/ha (down to right).
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Fig.10. Urban Dispersion histogram relative to Italian landscape kinds, obtained as ratio between
urban nucleus number (font: Corine Land Cover Level 3) and the surface in hectares of the
Physiographic Unites designed by APAT (National Agency for Environmental Conservation
and Technical Services) on 2004.
settlement structural characteristics and could be linked directly to the disturbance
typologies on the natural matrix.
Infrastructural Fragmentation Index: the fragmentation caused by road infrastructure may be assessed by means of separate indices according to the type of
infrastructure (motorways, railways, main roadways, local roadways, and overall
standardised index) depending on the different features of environmental obstruction
that each category entails for wildlife (ROMANO, 2002).
Infrastructural fragmentation may be measured using the Infrastructural Fragmentation Index (IFI):
IFI = ∑ (Li *oi) * li/Au where:
Li = Length of the infrastructure (excluding tunnels and viaducts);
oi = Obstruction coefficient of the infrastructure, depending on the type of infrastructure and traffic flow;
li = Road width;
Au= Area of the reference territorial unit;
In relation to obstruction coefficient, oi=1 in the case of motorways and railways
(total obstruction due to side fencing), while, in the case of roads with a high volume
of traffic (with significant obstruction due to noise and permanent movement), the
obstruction coefficient oi is expressed as a function of the traffic flow on the section
of the road considered.
In a given road section, with a traffic flow equal to n vehicles per hour, the time
during which the same section is free from transit is equal to:
_t = 1/n
If _t are equal, then the probability that wildlife will successfully cross the road
depends mainly on the theoretical speed of movement of the species, the width of
the road and the length and width of transiting vehicles.
These considerations clearly show that it is possible to develop a very detailed
44
coefficient of biological obstruction caused by roads, at scales where numerous
variables can be used.
If one remains at a territorial level of indicator processing, the latter may be
simplified by attributing an obstruction coefficient equal to the one of side-fenced
infrastructure (100%) when the traffic flow is equal to or greater than 60 vehicles/h.
This value tells us that the section of the road is free from transiting vehicles for
one minute on average.
Therefore, the obstruction coefficient may be related to the average daily traffic
flow per hour through the following relation:
oi = n/60
where n is the traffic flow expressed as the number of transiting vehicles per hour.
In general, the same road sections have very different traffic flows depending on
the season and times of the day and night. In this respect, the fragmentation effect of a
road varies undoubtedly and may be further assessed once relative data are collected.
Urban Fragmentation Index: on the basis of the consideration that, if the size of
settlements is the same, then the circular, polarised shape is the one that minimises
environmental fragmentation, linear urban fragmentation can be measured using the
Urban Fragmentation Index (ROMANO, 2002):
UFI =
ΣL * √ ΣS
i
i
Au
where:
Li = Maximum size of the linear urban barrier of the i type;
Si = Surface of the urbanised area of the i type;
Au= Area of the reference territorial unit;
oi = Coefficient expressing the level of obstruction that is characteristic of the various
types of urbanised areas for the species considered. By using a simplified rationale,
to obtain an indication at territorial level, the following values may be viewed as
significant:
a)Industrial areas and the like: oi =100%
Presence of concentrated pollution, heavy traffic, noise, lights and disturbance
even at night, presence of large paved areas, general lack of green areas.
b)Business districts and the like: oi =80%
Presence of large paved areas, night lighting, significant daytime traffic flows,
greater general presence of green areas and vegetation compared to case a).
c)Intensive residential areas: oi =60%
Presence of concentrated pollution, noise, daytime disturbance, general presence
of green areas and vegetation that is more distributed and widespread than in case
b).
d)Extensive residential areas: oi =40%
Scattered housing, greater spreading of disturbance, presence of vegetation and
green areas, both within private plots and in public areas, generally greater compared to case c).
Sensitiveness towards the use of land for widespread urbanisation can provide
a significant indication for the development of environment-friendly planning tools.
This involves understanding how an area will respond to the use of land due to the
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Fig. 11. IFI index calculated for Lazio Region (Central Italy) on the Physiographic Unites
(APAT 2004). [en couleur à la page 776]
Fig. 12. Relation between Urban density (UD) and IFI index on Lazio region landscape units.
gradual expansion of urbanised areas, following the creation of some favourable
conditions related to the geographical and social structure, as well as local and
external economic factors.
Total Settlement Fragmentation Index:
SFI = IFI + UFI =
Σ L o l +Σ L* √ Σ S
i i i
Au
The index gives the indication about the total fragmentation in the spatial unit
due to the combined effects of the infrastructures and linear urbanisation.
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Fig. 13. UFI index implemented on landscape units of Umbria region. [en couleur à la page 777]
CONCLUSION
With regards to the cited indices it is necessary to make some considerations:
first of all it is important to define level and dimension of the “minimal analysis units”
(MAU) in which are realized the observation and the interpretation of the phenomena
explain from the different indices.
Normally, in fact, these MAU are very small when are relative to eco-biogeographical data, and are instead larger when are relative to urban and territorial data.
At this aspect are link the major problems for implementing the correlation functions.
The “ecoregional approach”, already consolidated in the Landscape Ecology and
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Fig. 14. Sample of the total settlement fragmentation index (SFI) and its relation with Urban
density (UD) for Umbria region.
recently improved by WWF International for establishing the conservation policies
(BOLOGNA, 2005), could be a solution. In this case, at different levels of scientific
knowledge, the landscape system, subsystem or units could become the standard for
developing the ecological, biological and urban researches.
On the other hand we can find a further difficulties on methods and criteria to
produce the data and, consequently, on the necessary time: the eco-biogeographical
analysis needs of long time, many operators, large financial needs and have seasonal
problems. If we make the comparison of this last analysis with the urban settlement
analysis (generally ex-situ, with standard map layers and homogeneous instruments)
will have two speed for producing the information and an inevitable negative effect
on the comparison and relation procedures.
Realize the correlation models will be not easy until are not solved problems
and knowledge gaps on the elements that needs of direct data production in way not
deducible from different fonts.
We can say that certainly, to start from a present ecosystem balance condition,
the modification due to the urban transformation to create undoubtedly the variations on the species richness-isolation characteristics, and these variations will be
re-measurable in the next time.
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Fig. 15. Examples of relation between urban density and birds richness (number of species)
on province of Rome (Lazio Region) - Elaboration Battisti C., La Rovere M., Romano B.).
Coherent data give the possibility to find and apply relation diagrams among
different phenomena and, consequently, to arrive at the control models by means
statistical functions.
Some example of the cited correlation models can be product using some elaboration derived from a recent research program on Roma Province, and now in progress.
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